Field of the Invention
The present invention relates to an evaluation method for evaluating optical characteristics, a storage medium, an exposure apparatus, an exposure method, and a method of manufacturing an article.
Description of the Related Art
As one apparatus used in the manufacturing step (lithography step) of semiconductor devices and the like, there is an exposure apparatus which transfers a pattern of an original to a shot region on a substrate. In the exposure apparatus, a part of exposure light is absorbed in a projection optical system, and thus optical characteristics of the projection optical system may fluctuate under the influence of heat generated by the absorption. As a result, it may become difficult to transfer the pattern of the original to the shot region accurately.
Japanese Patent Laid-Open No. 63-58349 proposes a method of predicting a fluctuation amount of the optical characteristics of the projection optical system by using a model formula having an exposure amount, an exposure period, and the like as variables and controlling the optical characteristics of the projection optical system based on a predicted value. Japanese Patent Laid-Open No. 63-58349 also proposes a method of measuring the fluctuation amount of the optical characteristics, and determining a prediction formula based on an actually measured value and the predicted value so as to reduce errors generated in the predicted value.
In Japanese Patent Laid-Open No. 63-58349, the fluctuation amount of the optical characteristics is actually measured by using a mark on the original having a circuit pattern that should be transferred to the shot region. It is therefore impossible to detect an image of the mark in a region, on an image plane of the projection optical system, onto which the circuit pattern is projected. As a result, accurate determination of the prediction formula so to reduce the errors generated in the predicted value may be performed inadequately.